thomas



March 13, 1956 c, THOMAS 2,737,932

SUPPRESSION OF PREIGNITION Filed Dec. 50, 1954 @Ajo. 5PM

ATTORNEY -:SUPPRESSIN10F.BREIGNITI0N' fit ings-L. Thomas, Swarthmgre, *Pa, assignor "tojSun This invention relates fto the suppression of ipreignition and similaralifiiculties inrspark rignition internal rcbmbusztionrengines.

- Uncontrolled ignition, .i. e. zpreignitionzand .rel'atediproblemsisuchxas' "wild ping, is deleterious .;to internaLcombustion engine'operation :since .it :causesil'oss of engine :power and overheating of .the engine. Higher octane :fuels .aremquiredtosuppress enginerpreignition.

Pnei'gnition. of the .enginefuel-air mixture is. caused .by contact with-glowing tor 'burning "carbonaceous material which is deposited in the combustion chambers of internal combustion engines; Such carbonaceous deposits result from decomposition of the hydrocarbon fuel and/ or lubricant used in the engine. It is known that products resulting from decomposition of various fuel or lubricant additives such as tetraethyl lead become incorporated in the carbonaceous combustion chamber deposits and catalyze ignition and glowing of combustible material in these deposits at lower temperatures, thus greatly aggravating problems of uncontrolled ignition.

Through practice of the present invention, preignition and related problems in spark ignition internal combustion engines are substantially completely overcome. According to the invention, organo-metallic compounds are decomposed in the combustion chambers of a spark ignition engine to form material which becomes incorporated in carbonaceous combustion chamber deposits and which catalytieally promotes low temperature oxidation of the carbonaceous deposits. Air is then introduced into the engine combustion chambers in addition to the air normally in the fuel-air mixture, which additional air oxidizes the carbonaceous deposited material, at such time as does not interfere with normal operation of the engine. It has been found that through practice of this invention, spark ignition engine combustion chamber deposits are rendered incapable of serving as a source of uncontrolled ignition, and accordingly preignition and related problems are overcome.

The organo-metallic compounds used in this invention decompose to form materials which catalyze carbonaceous deposit ignition and combustion at temperatures lower than those at which the decomposition products of lead anti-knock agents promote deposit ignition. The organo-metallic compounds are incorporated in the internal combustion engine fuel preferably, although such compounds can be incorporated in the lubricant or in both fuel and lubricant used in the engine. The organo-metallic compounds are preferably soluble in the fuel and/or lubricant. Suitable compounds which are used in practice of the invention are soluble organic compounds of variable valence metals such as copper, manganese, cobalt, cerium, tungsten, vanadium, molybdenum, and the like. Traces of compounds of alkali metals such as potassium or sodium can be used in combination with compounds of the foregoing metals to further improve deposit combustion catalysis. These organo-metallic additives decompose at conditions in spark ignition engine combustion chambers to form products, e. g. metal oxides, which catalyze de- A United States Patent 2,737,932 Ratented Mar-.13, 19 56 cpositrcombustion at lower. temperatures, than :-.similar ;de

composition'products of lead Eantiknock zagcntsne; g; detra- -ethyl dead. n :It is important that .thevadditive decomposition products of .this invention catalyze deposit combustioncat c-substantially lowentemperatures than lead additive idercomposition products in order that the deposits the completely ox-idized..-b,y practice of this invention andrtlt'us rendered incapable of serving as a:s'ourcexof preignitio'n.

.Soluble .compoundsof the above metals .are added'tothe :eng-ine ,xfuelaand/ or lubricant :according :to the invention.

. Suitable soluble compounds are :thosezorganometaliic' .compounds formed by reacting the metalsor compounds of the metals with .naphthenic acids, higherpariafiinsor "1611318, e. ,=g. metaL-oxides, which :become incorporated in carbonaceous combustion chamber deposits and which act as oxidation catalysts therein.

In practice of this invention, the organo-metallic compounds described above are used in a spark ignition engine which has means for supplying oxidizing air to the engine combustion chambers at such time as does not interfere with the normal engine operation.

' The accompanying drawing illustrates in simple diagrammatic form an internal combustion engine apparatus which is preferably used in the practice of this invention. Engine 1 represents a standard internal combustion engine. Engine 1 is connected by intake manifold 2 to carburetor 3. Positioned between carburetor 3 and the engine cylinders 4 is a valve 5 which is adapted when open to admit oxidizing air into the engine cylinders 4. Valve 5 is held normally closed by spring 6. Solenoid 7 is adapted when activated to open valve 5 against the force of spring 6. Activation of the solenoid is regulated by a circuit including throttle switch 8, relay 9, generator 10, and battery 11 such that the solenoid is activated with power drawn from battery 11 only when the throttle is closed and the generator 10 is charging. Solenoid 7 is connected to throttle switch 8 which is adapted to close the solenoid activation circuit only when the engine throttle is closed. Switch 8 is connected in turn to relay 9. Relay 9 is connected both to generator 10 and battery 11 such that when the generator is not charging-the solenoid activation circuit is open and the solenoid is inactive. However, when the generator is charging, the solenoid circuit is closed at relay 9 and if the throttle switch 8 is also closed the solenoid is activated thereby opening valve 5. This operation insures that oxidizing air is admitted in the combustion chambers of engine 1 only when the throttle is closed and the generator is charging, e. g. when an automobile is rapidly deaccelerating or coasting downhill with the throttle closed.

The apparatus described above and shown in the accompanying drawing is disclosed and claimed in copending application Serial No. 478,792 of Russell H. Kent, Jr. of even filing date herewith. The apparatus itself is not part of this invention. The present invention comprises the method of using the apparatus with the organo-metallic fuel and/ or lubricant additives described above, and is separate and distinct from the invention claimed in the above copending application.

A conventional scavenging-type engine may also be used in the practice of this invention. Scavenging engines have as part of the engine operating cycle a period when air is admitted to the engine combustion chamber for purposes of scavenging exhaust gasestherefrom. Such engines are well known in the art; an example of a scavenging engine can be found in U. S. Patent No. 1,982,554.

According to the present invention, these engines having means whereby oxidizing air is admitted to the engine combustion chambers are operated using the soluble organometallic fuel and/ or lubricant additives described above. The organo-metallic compounds decompose in the engine combustion chambers to form material which catalytically promotes oxidation of combustible material in the carbonaceous deposits. With the admission of the oxidizing air during engine operation as described above, carbonaceous deposits are oxidized and thus rendered incapable of serving as a source of uncontrolled ignition in subsequent engine operation. With continued engine operation and admission of oxidizing air, the combustion chamber deposits are maintained continually substantially free of combustible material. Accordingly, preignition and related problems are overcome by practice of the invention.

Practice of this invention is particularly advantageous where lead organo-metallic compounds such as tetraethyl lead are used as anti-knock additives since normally systems using such additives have the worst preignition problems as a result of the catalytic eifect of the lead decomposition products.

It is to be noted that the organo-metallic fuel and/or lubricant additives used in practicing this invention, if used in a standard spark ignition engine having no means for supplementary air supply, would aggravate preignition problems by their catalytic effect at low temperatures.

I claim:

1. The method of suppressing preignition in spark ignition internal combustion engines which comprises: decomposing in the combustion chambers of said engine organo-metallic compounds which form decomposition products which catalyze combustion chamber deposit oxidation at lower temperatures than lead anti-knock agent decomposition products do, and subsequently during engine operation injecting air into the combustion chamber in addition to the air normally supplied to the combustion chamber in the air-fuel mixture, thereby to oxidize combustible material in combustion chamber deposits and to render such deposits substantially incapable of serving as a source of uncontrolled ignition.

2. The method according to claim 1 wherein said organo-metallic compounds are compounds of metals selected from the group consisting of copper, manganese, cobalt, cerium, tungsten, vanadium, and molybdenum.

3. The method according to claim 1 wherein said organo-metallic compounds comprise compounds of metals selected from the group consisting of copper, manganese, cobalt, cerium, tungsten, vanadium, and molybdenum in combination with compounds of alkali metals.

No references cited. 

1. THE METHOD OF SUPPRESSING PREIGNITION IN SPARK IGNITION INTERNAL COMBUSTION ENGINES WHICH COMPRISES: DECOMPOSING IN THE COMBUSTION CHAMBERS OF SAID ENGINE ORGANO-METALLIC COMPOUNDS WHICH FORM DECOMPOSITION PRODUCTS WHICH CATALYZE COMBUSTION CHAMBER DEPOSIT OXIDATION AT LOWER TEMPERATURES THAN LEAD ANTI-KNOCK AGENT DECOMPOSITION PRODUCTS DO, AND SUBSEQUENTLY DURING ENGINE OPERATION INJECTING AIR INTO THE COMBUSTION CHAMBER IN ADDITION TO THE AIR NORMALLY SUPPLIED TO THE COMBUSTION CHAMBER IN THE AIR-FUEL MIXTURE, THEREBY TO OXIDIZE COMBUSTIBLE MATERIAL IN COMBUSTION CHAMBER DEPOSITS AND TO RENDER SUCH DEPOSITS SUBSTANTIALLY INCAPABLE OF SERVING AS A SOURCE OF UNCONTROLLED IGNITION. 